Automation Flashcards
What is an internal relay?
A computer generated device that has functions to control other devices
What is an internal timer?
A computer generated device that times in mS and can only be a on delay timer.
Internal counter?
Is a computer generated device that when an item or object passes through the device gets counted up and once reached a certain amount will perform a different function.
Pulse bit?
Is a computer generated device that will pulse and output and certain intervals to what it is set at.
What are the main 4 parts of a PLC?
Power supply
CPU (Central processing unit)
Input/Output Modules
Programming terminal
(5th is Rack)
What numbering system is based on 2 digits?
Binary
What numbering system is based on 8 digits? (0-7)
Octal
What numbering system is based on 10 digits?
Decimal
What numbering system is based on 16 digits
Hexadecimal
Which industry first used PLC’s?
Automotive industry
A PLC is a special kind of…?
Industrial computer
Most PLC’s are designed to be programmed in?
Ladder logic
A PLC power supply must be able to regulate voltage within?
5% of the required value
In a PLC all functions are performed by the?
CPU (Central Processing Unit)
Manufacturers use one of two devices to prevent a program from being accidentally deleted. What are they?
Software key and physical key
What is another name for the programming terminal?
Loading terminal
The PLCs terminal is used to?
a. Program the controller
b. Monitor the cpu and
c. Troubleshoot
Are NEMA symbols such as pushbuttons, limit switches or selector switches used in PLC ladder diagrams?
No. Only NO and NC contacts
How are contacts of a PLC ladder diagram addressed?
By a number/ contacts address
If a laptop or notebook computer were connected to a PLC the laptop or notebook computer would be referred to as the…
Programming terminal
In a ladder diagram each rung ends with a?
Coil
How are coils of a plc ladder diagram symbolized?
Brackets
What part of the PLC is referred to as the brains
CPU
What type of isolation is generally used to electrically separate outside voltages from the internal circuitry of the PLC?
Optical isolation
What is connected across the AC input to help eliminate any voltage spikes that may occur on the line?
Metal Oxide Varistor (MOV)
What part of the PLC connects the CPU to the real world input/output devices?
The input/ output modules
If an output module controls a DC voltage what solid state device is used to connect the load to the line?
power phototransistor
If an output module controls an AC voltage, what solid state device is used to connect the load to line?
Triac or Phototriac
What are timers and counters in a PLC
Computer generated and internal relays
Pushbuttons limit switches and float switches would be considered
Input devices
When a PLC utilizes opto isolation what device is used to either signal the CPU that a voltage is present at the input terminal or the CPU to signal a solid state device to connect the line to load?
LED (Light emitting diode)
The amount of current output modules can handle is generally
0.5A- 3A
When may an interposing relay be used?
When the amperage of the load exceeds the rating of the output module
If a PLC is used to start a 3 phase motor the output module is used to what?
Energize the motor starter coil
A PLC recognizes internal relays and timer contacts by what?
The contacts address
What are the 5 basic logic gates?
And
Or
NAND
NOR
Inverter
Transistor transistor logic (TTL) operates on
5 Volts
High transit logic (HTL) operates on what?
15 volts
Most gate circuits are multi input what output devices?
Answer “what”
Single output
How many input and output does the inverter have?
1 of each
When an inverter gate is used is the input or output inverted?
Output
Explain an AND gate
If all inputs are high the output is high
( Both inputs have to be high to have an output)
Explain an OR gate
If one input is high the output is high
(Only one input has to be high to have an output, can be either or)
Explain a NOR gate
If one input is high the output is low.
To get a high output both input have to be low
Explain a NAND gate
If all inputs are high the output is low!
If both inputs are low the output will be high
A logic gate in which the output is always the opposite the input is the
INVERTER
What symbol is used to represent “INVERT” when NEMA or computer logic symbols are used?
X
If an inverter is connected to the output of an AND gate what logic gate is formed?
NAND gate
If an inverter is connected to the output of an OR gate what logic gate is formed?
NOR gate
When using a two input AND gate what conditions of input must be met to get an output?
Both inputs must be high
When using a two input OR gate what conditions of input must be met to have an output?
Either input may be high
When using a two input NAND gate what conditions of input must be met to have an output?
Both inputs must be low
When using a two input NOR gate what conditions of input must be met to have an output?
Both inputs must be low
The gate that is referred to as the basic gate is the?
NAND gate
A NOTO contact is from an ON or OFF delay timing relay?
Off delay
What is the term that is typically used to describe the high and low settings of a float switch, pressure switch or a temperature switch?
Differential setting
What devices could be used to monitor the current of a 3 phase motor?
Current transformer
A control circuit that allows a piece of equipment to re start after a power interruption is called what?
Low voltage release
